java - How to convert an ArrayList containing Integers to primitive int array? -

java - How to convert an ArrayList containing Integers to primitive int array? -

i'm trying convert arraylist containing integer objects primitive int[] next piece of code, throwing compile time error. possible convert in java?

list<integer> x = new arraylist<integer>(); int[] n = (int[])x.toarray(int[x.size()]);

you can convert, don't think there's built in automatically:

public static int[] convertintegers(list<integer> integers) { int[] ret = new int[integers.size()]; (int i=0; < ret.length; i++) { ret[i] = integers.get(i).intvalue(); } homecoming ret; }

(note throw nullpointerexception if either integers or element within null.)

edit: per comments, may want utilize list iterator avoid nasty costs lists such linkedlist:

public static int[] convertintegers(list<integer> integers) { int[] ret = new int[integers.size()]; iterator<integer> iterator = integers.iterator(); (int = 0; < ret.length; i++) { ret[i] = iterator.next().intvalue(); } homecoming ret; }

java arrays arraylist primitive-types